Neurochemical studies on catecholamines and indoleamines by high-performance liquid chromatography with electrochemical detection

Summary

This communication reports the HPLC separation and quantitative ECD assay of dopamine (DA) and its metabolites DOPAC and HVA, 5-HT and its metabolite 5-HIAA and the noradrenaline metabolites MHPG and VMA, in samples of rat brain extracts and human CSF. The separation is carried out by reversed-phase with a methanolic phosphate/citrate buffer as mobile phase. Response is linear within 10pg-20 ng. Rat brain homogenates of cortex plus striatum were centrifuged and 10–20 μl aliquots injected in the column. CSF samples were directly injected without any further manipulation. The method has been applied to the study of the possible neuromodulating role of T on the catecholaminergic and serotonergic transmission. For this purpose rats are injected intraperitoneally (ip) with T (150 mg/kg) and killed after 30 min. Relative to control rats, the results show that for n=12, T does not affect the basal level of DA and DOPAC whereas HVA increases a 99.3% and 5HT and 5HIAA show variations of 23% and — 4.1%, respectively. Aside from the fall of 5HIAA, it is interesting to note that the turnover rate of 5HT decreases, which might prove of functional significance.